There is a strong relationship between hospital and surgeon volume and outcomes of total joint replacement. Therefore, regionalization, the movement of cases from low volume hospitals to high volume hospitals, of elective total joint replacements may be beneficial. The possible benefits of regionalization include improved patient outcomes and lower health care costs through a decreased rate of complications and revision surgery. However, the benefits of regionalization may not be equitably distributed if traditionally underserved patients face barriers to seeking regionalized care. Differential access to regionalized surgical care could possibly widen health disparities that already exist. The aims of this research are: 1) to describe the frequency and predictors of regionalization of elective total joint replacement in the US;and 2) to assess whether regionalization for elective total joint replacement is associated with improved short-term patient outcomes. These aims will be accomplished by identifying the percentage of patients undergoing total joint replacements who traveled beyond their hospital service area (HSA) to undergo total joint replacement at a higher volume hospital in another HSA. Those who receive care in their local HSA will be considered "localized" while those who receive care elsewhere will be considered "regionalized." Patients will be identified through existing hospital discharge databases for 21 states throughout the US. The effects of patient, age, sex, race/ethnicity, insurance status and comorbidity on the likelihood of receiving regionalized care will be evaluated using multivariable repeated measures models including methods that account for the correlation of procedures performed by the same surgeon or within the same hospital. To determine whether regionalization improves short-term outcomes, rates of surgical complication and revision procedures will be compared between patients who regionalize and those who do not, adjusting for potential confounders. The results of this research will provide important insights regarding predictors and outcomes of regionalized orthopedic care. If regionalization is associated with reduced rates of surgical complications and revision procedures, and if regionalization is less common among traditionally underserved populations, then interventions to increase access to regionalized care may reduce disparities in outcomes of total joint replacement.